An inkjet printer for dispensing ink droplets on a medium, such as paper, to form images or characters is known. Inkjet printers include an inkjet head which ejects the ink droplets according to an image signal.
The inkjet head includes a nozzle from which ink droplets can be ejected, an ink pressure chamber communicating with the nozzle, and an actuator which generates pressure for causing ink to be ejected from the nozzle. The actuator includes a piezoelectric body. A piezoelectric element, also referred to as a piezo element, included in the piezoelectric body, is an electromechanical conversion element to convert a voltage into force. The deformation of the piezoelectric element is used to generate pressure in ink contained in the ink pressure chamber. The pressure generated in ink causes ink to be ejected from the nozzle. A typical material of the piezoelectric element includes piezoelectric lead zirconate titanate (PZT).
An inkjet head which operates using shear deformation of a piezoelectric body is known. This type of an inkjet head includes a piezoelectric body having a groove serving as an ink flow path formed thereon, an electrode formed on an inner surface of the groove, a nozzle plate having nozzles formed therein to eject ink, and a protective film covering the electrode. The nozzle plate is bonded to the upper surface of the piezoelectric body in such a manner that each nozzle corresponds to a groove formed on the piezoelectric body. The electrode is formed not to extend to the upper surface of the piezoelectric body. The electrode not extending to the upper surface of the piezoelectric body prevents or reduces the deformation of the nozzle plate bonded to the piezoelectric body.
In the inkjet head configured as described above, the protective film covering the electrode is considered insufficient in insulating property.